Blindness Breakthrough

According to a recent study, head-mounted, compass-like devices connected to the brains of blind rats have allowed them to navigate a maze almost as well as normal-sighted rats. Researchers indicate that a similar technique could be used to help blind humans navigate. The researchers, Yuji Ikegaya and Hiroaki Norimoto of the University of Tokyo, pubished the details of their creation in the journal Current Biology. Approximately 39 million people around the world are blind, 82% of whom are 50 or older. Blindness interferes not only with vision, but also spatial awareness (“allocentric sense”), or a person’s ability to recognize the position of their body relative to their surroundings.

For their study, the researchers set out to see if they could restore allocentric sense of “blind” adult rats by stimulating the visual cortex in their brains. They created a lightweight head-mountable sensor device made up of a digital compass (the same as those found in smartphones) connected to a microstimulator with two electrodes. Once implanted into the visual cortex of the animals’ brains, the device was able to detect their head movements and generate an electrical stimulation, or “geomagnetic signal”, informing the animals which direction they were facing.

The researchers set out to test whether the device could guide the blind rats through a maze, effectively restoring their allocentric sense. With the devices attached, the rats were trained to seek food pellets in the T-shaped maze, as well as more complicated maze shapes. Their ability to solve each maze was compared with that of normal-sighted rats, who could depend on visual cues to reach the food pellets. Ikegaya and Norimoto found that within 2-3 days of maze training, the blind rats learned to use the geomagnetic signal triggered by the device to find the food pellets. The researchers say that these findings demonstrate just how the mammalian brain is able to learn and adapt to new information well into adulthood.

From their research, the team believes that the findings could be applied to humans, with geomagnetic sensors being attached to the walking sticks of blind people to help them navigate their surroundings. The researchers say that a geomagnetic sensor device similar to the one used in their study may be effective for restoring allocentric sense in blind people, and that artificial sensors could even be used to detect ultraviolet radiation and ultrasound waves.